The 62-year-old actor is seeking treatment at Hazelden Addiction Treatment Center in Minnesota to help him maintain his long-term sobriety.

His representative told TMZ.com: "After working back-to-back projects, Robin is simply taking the opportunity to fine-tune and focus on his continued commitment, of which he remains extremely proud."

It is believed Williams will be spending the next several weeks at the facility seeking professional help.

In 2006, the comedian checked himself into a substance abuse rehabilitation centre in Oregon after admitting he was an alcoholic following two decades without booze.

His publicist said at the time: "After 20 years of sobriety, Robin Williams found himself drinking again and has decided to take proactive measures to deal with this for his own well-being and the well-being of his family."

The Mrs Doubtfire star also battled with cocaine addiction in the late 1970s and early 1980s, but quit the drug following the death of his close friend John Belushi in 1982 and the birth of his son Zachary in 1983.

Williams previously admitted he once thought he could handle his substance abuse on his own, but realised he would only kick his addiction with professional help.

He said: "You can't [deal with it on your own]. That's the bottom line. You really think you can, then you realise, I need help, and that's the word ... It's hard admitting it, then once you've done that, it's real easy."

Meanwhile, the star has been busy working on the upcoming movie Night at the Museum: Secret of the Tomb, which is expected to hit screens later this year.